Double-modified guar gum dual-network hydrogels with balanced mechanical and swelling properties

Polysaccharide-based hydrogels suffer from an inherent trade-off between mechanical strength and swelling capacity, along with poor structural stability under complex conditions, which severely restricts their industrial scalability. Herein, a targeted dual-side-chain modification strategy (hydroxypropylation combined with phosphation) was developed, and a rigid-flexible dual-network (DN) hydrogel was constructed via the interpenetrating of modified guar gum derivatives with polyacrylamide (PAM). A critical crosslinking density threshold of 0.1 g/10 g system was identified, where the rigid modified guar gum backbone and flexible PAM network formed a homogeneous interpenetrating structure. This unique structure enabled the hydrogel to achieve a compressive strength exceeding 500 ± 26 kPa and swelling ratio of 46-fold, realizing an excellent balance between mechanical performance and swelling behavior. For extreme agricultural scenarios, the borate-ion-crosslinked B(OH)₄^--HPG/PAM hydrogel retained 85% of its mechanical properties under high temperature and salinity. For acidic complex wounds, the phosphorylated Ca²⁺-PGG/PAM hydrogel (esterification degree 0.12 ± 0.01) exhibited a superior swelling ratio via pH-responsive dissociation of coordination bond. This scenario-adaptive bio-based hydrogel constructed via rational molecular modification provides a feasible solution for agricultural water retention in extreme environments and advanced dressings for complex wounds, and offers a design paradigm for polysaccharide-based hydrogels with balanced mechanical-swelling properties.